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luke smith

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i just put a new 4.3L in my 19

i just put a new 4.3L in my 1993 2252 bayliner runs great but any idea what the wot should be or how fast it should go. im getten 27 mph @4200rpm with a 17pitch ss prop seems a little slow . cant find specs on what the boat did new? any info would be great
 
prop sounds a little small but

prop sounds a little small but no sure what kinda bayliner you got. I have a 19.6 foot open bow and I run a 14.25 by 21 with a cupp and a 3.7L four cyclinder and it runs 4800 in the mid 40's
 
"You should be running ~ 4700

"You should be running ~ 4700 to 4800 rpms,

1. 4.3 in a 22 ft is a bit small so MPH will also be small.
2 Every pitch change is typically ~ 300 rpms change, example: your 17 gives 4200, go to a 15 p and you will get ~ 4500.

I am not that good with props but I believe what you need is a larger diameter to move more water.

The one you are using is (just a guess) 14 0r 14.25 diameter. You may need the next larger diameter.

That is a lot of boat for a 4.3 litre"
 
"I had a 2150 Bayliner cuddy w

"I had a 2150 Bayliner cuddy with the little 3.0 and it went 33 mph or so - you should be in the 30's...the weight question is valid...any soft spots in the floor, water logged flotation foam will slow you down"
 
"ahhhhhhhhhhh... here is the c

"ahhhhhhhhhhh... here is the cheat sheet i picked up here a while ago.....<center><table border=1><tr><td>http://www.marineengine.com/discus/icons/mime_msexcel.gif""" align=left alt=""application/vnd.ms-excel"">
[url=""][b]Copy of Boat_Speed_Finder-79780.xls[/b][/url] (22.5 k)</td></tr></table></center>"
 
"If you are only getting 4200

"If you are only getting 4200 RPM out of that setup and the engine is supposed to rev up to 4700 to 4800 RPMs, then the prop is TOO LARGE!
Changing from a 17Pitch to a 15 pitch will allow the engine to rev higher, but you may not end up with all that much more (or ANY) boat speed.
Running the boat with a prop that does not allow full rated WOT RPMs ( in your case 4700 RPMs) can result in damage to the engine. Sounds to me like the P/O wanted to go faster and increased the prop size, but it did not result in the correct RPM range. 4.3L is not a lot of engine for a boat that size. I have a 23 ft boat (ChrisCraft Deep V) and run a 260 HP 5.7L (V8)engine and a 21 Pitch Prop. Wide open is 37 MPH."
 
"TOO LARGE""

No

"TOO LARGE""

Not quite correct............

The pitch is to steep of an angle not the diameter...........

You can have "a" pitch but several different diameters..........

What he may need here is what I refere to as a "spoon" prop. The blades are quite big.
this type will definatley push some water....
 
"R A F,

I would say your 23

"R A F,

I would say your 23 ft CC is quite under powered also. No reason you should not be able to run ~ 42-45 maybe a bit more with no effort.

I said this before and I feel it is the way boats should be built.

16-17/18 ft can use 4 cyl.

18-19 v6 min some 19's need a V8 small block.
20-22 lighter boats V8 350 CU Inch minimum.

22 and up BIG BLOCK....PERIOD!!!!

One other combo I know works extremely well is a 22-24 cuddy type design with a 350 V8 and a Bravo 2.
Will make it POP out of the water as if it were on steroids..........."
 
"Kghost..

Re: Too large...I

"Kghost..

Re: Too large...I should have been more specific, too much pitch (for the diameter)

Re: my 23 ft... Actually, it does underperform. While the engine is a Merc, the I/O is a Volvo.
The exhaust port on that particular drive is a bit undersized @ 2.5" MERC manual says 2 X 3" or 1 X 4" ports for the 5.7L MIE engine that I have. Engine does not reach full WOT (3850 max). At full factory WOT and the existing prop, it should go 42+ per my calculator. Going to thru transom w/mufflers (State law) next spring which should fix the problem. I had wanted to go thru transom when I put the new engine (was a 185HP 283CID) in but I let the mechanic who was doing the job talk me out of doing that. Boat is a 69 ChrisCraft Lancer (cuddy) which has a fairly deep V. While a big block would be nice, I boat on Barnegat Bay and it gets a bit "rough", even for a Deep V. Doing anything near 40 mph is very "exciting" most times :)"
 
the 4.3.l came stock with the

the 4.3.l came stock with the boat @210 h.p feel i should go faster but cant find orignal info for the boat
 
"I put some numbers in the for

"I put some numbers in the formula and it appears a 21P prop will get your boat into the mid 40s. I used 3600 lbs. for the weight and guessed the OD gear 1.81 ratio. ANYBODY: change what I put in wrong.

<center><table border=1><tr><td>http://www.marineengine.com/discus/icons/attachment_icon.gif""" align=left alt=""application/octet-stream"">prop finder
[url=""][b]Copy of Copy_of_Boat_Speed_Finder-79780-193827.xls[/b][/url] (26.1 k)</td></tr></table></center>"
 
"Jeff;
I beg to differ.
My o

"Jeff;
I beg to differ.
My old 180 hp 4.3 swung a 21" High Five just fine with the 1.81 drive (same as Luke's) and a 2950 lb boat. WOT peaked at about 4800 rpm, right on spec. Made 47 mph no problem.
It all depends on the weight, which I guess we don't know.

Rod"
 
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